Suckling mousebrain (SMB) rabies vaccine is the preparation most widely used in the countries of Latin América and the Caribbean. This vaccine, prepared according to the Fuenzalida and Palacios method, consists of three fixed rabies virusstrains (CVS, 51, and 91). However, the World Health Organization recommends that rabies vaccines for human use be prepared using only a single strain of this virus. In order to determine whether any one of the antigens of the SMB vaccine could be eliminated from the preparation, the immunogenic capacity of the standard trivalent SMB vaccine was compared with that of experimental bivalent (CVS-51, CVS-91, and 51-91) and monovalent (CVS, 51, and 91) SMB vaccines. The study was conducted using adult and suckling albino mice provided by the laboratory at the Pan Américan Zoonoses Center, Buenos Aires, Argentina, and different strains of fixed and street rabies virus. The experimental vaccines were prepared using the Fuenzalida-Palacios method. Potency and cross-immunity tests were conducted. The result showed that the trivalent vaccine was the most effective in protecting the mice againg both fixed and street rabies virusinfections and also in inducing rapid development of neutralizing antibody at high titers